The technical performance requirements of microelectromechanical systems (MEMS) inertial measurement units (IMUs) have been challenging to meet for military, aerospace and high-end industrial and commercial market applications. Such high-end performance goals are, for example, that the bias and scale factor stability of the IMUs should be better than 1°/hr and 10 ppm for a gyroscope and better than 1 mg and 1 ppm for an accelerometer across a −40° C. to +85° C. temperature range.
Using an ovenized platform is intended to improve a given device's performance stability by holding the device at a relatively uniform stable temperature in a vacuumed enclosure. Such an approach isolates the devices from the environmental changes and facilitates the achievement of the abovementioned high performance goals. Over the past two decades, utilizing long suspended silicon support structures has become a common approach in MEMS fabrication in an attempt to provide the desired thermal isolation for a suspended silicon platform. However, this approach is often plagued with a number of drawbacks and limitations. For instance, due to the high thermal conductivity of silicon, in order to achieve the thermal isolation requirements necessary for the accurate performance of an IMU, the suspended silicon structures need to be very long and compliant and are, therefore, not very suitable for inertial sensing applications.
Additionally, until now, a glass substrate has been used to facilitate thermal isolation in the fabrication of the ovenized platform due to the very low thermal conductivity of SiO2. However, the deficiency of this method is that the fabrication process of a glass platform is typically not compatible with standard complementary metal-oxide-semiconductor (CMOS) and MEMS manufacturing processes. Sensor and platform integration can often be achieved on a die-level assembly making glass an impractical substrate. Furthermore, although there is a requirement for the temperature gradient inside the platform is to be minimized, such a requirement is difficult to meet with a low-conductivity material such as glass. Further, the thermal mismatch between glass platform and mounted sensor can potentially cause large stress when the platform form temperature increases.
Accordingly, there is a need in the art for an ovenized silicon platform with high technical performance specifications. More specifically, there is a need for a micro-oven platform incorporating a MEMS IMU providing high-temperature isolation as well as low-displacement and high-shock survival in the face of environment vibrations and mechanical impacts with unprecedented bias and scale factor stability that is fully compatible with accepted CMOS and MEMS fabrication processes. These and other features and advantages of the present invention will be explained and will become obvious to one skilled in the art through the summary of the invention that follows.